1624 (first used by Capt. John Smith, in reference to Virginia), perhaps a dialectal survival from an Old English cognate of Old Norse svoppr "sponge, fungus," from Proto-Germanic *swampuz; but traditionally connected with Middle English sompe "morass, swamp," probably from Middle Dutch somp or Middle Low German sump "swamp." Related to Old Norse svöppr "sponge." Swamp Yankee "rural, rustic New Englander" is attested from 1941.

v.

"overwhelm, sink (as if in a swamp)," 1772, from swamp (n.). Figurative sense is from 1818. Related: Swamped; swamping.